Unexpected Macrocyclic Multinuclear Zinc and Nickel Complexes that Function as Multitasking Catalysts for CO₂...

Area of Science:

• Coordination Chemistry
• Catalysis
• Supramolecular Chemistry

Background:

• Macrocyclic complexes offer unique structural and catalytic properties.
• Multinuclear metal complexes can exhibit cooperative effects in catalysis.
• Binaphthyl-bipyridyl ligands provide a versatile platform for constructing complex architectures.

Purpose of the Study:

• To synthesize novel self-assembled macrocyclic multinuclear Zn(II) and Ni(II) complexes.
• To investigate the structural features and dynamic behavior of these complexes.
• To explore their dual catalytic activities in CO2 fixation reactions.

Main Methods:

• Synthesis of multinuclear Zn(II) and Ni(II) complexes using binaphthyl-bipyridyl ligands.
• X-ray crystallography for structural elucidation.
• Nuclear Magnetic Resonance (NMR) spectroscopy to study dynamic processes in solution.
• Catalytic reaction monitoring for CO2 fixation.

Main Results:

• Successfully synthesized unique macrocyclic multinuclear Zn(II) and Ni(II) complexes with a distinct outer ring and inner core structure.
• Observed rapid intramolecular rotation of the inner Zn2 core within the outer Zn3L3 ring in the Zn(II) complex via NMR.
• Demonstrated dual catalytic functions: efficient synthesis of cyclic carbonates from epoxides and CO2, and temperature-switched N-formylation/N-methylation of amines using CO2 and hydrosilane.

Conclusions:

• The synthesized macrocyclic multinuclear complexes possess unique structural and dynamic properties.
• These complexes serve as efficient dual catalysts for important CO2 fixation transformations.
• The findings open avenues for designing sophisticated catalysts for sustainable chemistry applications.